Electric conductor



(NoModel.)

J. A. BARRETT.

ELECTRIC CONDUCTOR.

110.462,681. Patented Nov. v10, 1891.

Tm: News rusas co., loro-umn.. wAsHmnro, n. rv

UNITEDA STATES PATENT OFFICE.

JOHN A. BARRETT, OF BROOKLYN, NEW YORK, ASSIGNOR TO THE STANDARD UNDERGROUND CABLE COMPANY, OE PITTSBURG, PENNSYLVANIA.

ELECTRIC CONDUCTOR.

SPECIFICATION forming part of Letters Patent No. 462,681, dated November 10, 1891. Application filed January 8, 1891. Serial No. 377,085. (No model.)

To all whom it may concern,.-

Be itknown that I, JOHN A. BARRETT, a citizenl of the United States, residing at Brooklyn, county of Kings, and State of New York, have invented certain new and useful Improvements in Electric Conductors, fully described and represented in the following specification and the accompanying drawings, forming a part of the same.

This invention relates to the manufacture of insulated electrical conductors, and especially to that class of electrical conductors in which the conductor is directly surrounded by a cover or serving of insulating material and the insulated conductor inclosed in an envelope of suitable material, preventing or retarding the passage to the insulating' cover or serving of a sealing material applied outside the envelope. In my prior Letters Patent No. 424,751, April l, 1890, is shown a conductor and cable of this class, in which the insulation next the conductors consists of fibrous or meshed material forming` air-spaces, so that the con ductor is insulated largely by dry' air, and the invention in the present case is especially designed as an improvement upon the construction shown in that patent. In my patent an envelope consisting of a strip of paper or other suitable material wound about the served conductor is shown and described.

The object of the present invention is to provide an improved envelope which, while occupying but a small space, shall prevent to the greatest extent possible the passage of the sealing material, and, further, to provide such an envelope in the form of a strip, which may readily be applied by winding it about the served conductor. I attain these objects by applying to the envelope a material which will form a permanent glazed surface thereon and render the envelope less liable to be penetrated by the sealing material. I -find that either mucilaginous, gelatinous, or albuminous compounds maybe used to form the material applied to the envelope, and for convenience I apply the term sizing7 to any material of the three classes mentioned which may be found to produce the desired result.

The envelope is preferably made of some 5o thin but tough paper, such. as manila; but

any other suitable material-such as thin muslin or other cloth-may be used with fairly good results. The sizing may be applied to either or both sides of the envelope,

so as to iill the pores of the material and form a glazed surface thereon, but for convenience in handling will preferably be ap* plied only to the inner side.

The envelope may be applied in any manner desired, but is preferably formedby wind- 6o ing a strip of the sized material abouta served conductor or pair of conductors, and the sizing is preferably of such a character that when moistened it will be adhesive and secure together the successive windings of the envelope, thus preventing the passage 'of the sealing material between the folds. Moreover, as a conductor and cable are subject to frequent flexure in use, it is-desirable that the sizing should be of suoli a character as 7o to bend readily when dry, in order to prevent, as far as possible, the cracking of the sizing upon the surface of the paper or in the joints as the envelope is bent.

IVhile many sizing materials of the three classes mentioned above will answer my purpose to some extent and may be used for forming a glazed surface upon the paper to prevent the passage of the sealing material, I prefer to use a pure dextrine gum, which 8o not only is cheaper than other compounds of the classes named, but has been found to answer my purpose more fully on account of its adhesiveness when moist and ability to stand bending without cracking when dry.

In the accompanying drawings, forming part of this specification, Figure l shows a braided and partially enveloped air-insulated conductor. Fig. 2 shows a pair of conductors inclosed in a single envelope for use in tele- 9o phone-work. Eig. 3 is a cross-section of a cable formed of single conductors, and Fig.

4 is a crosssection of a cable formed of pairs of conductors.

In the drawings, a is the conductor, and l) the 95 air-containing serving, which is shown in the present case as formed of braided thread or cord, but which, it is evident, may be applied in any other manner, as shown and described in my patent above referred to. The envel- Ico ope consists of a strip, preferably of tough Manila paper, sized as described above and wound about the serving, so as to form a continuous outer covering therefor.

The sealing material may be applied to the envelope surrounding a single conductor or a pair of conductors, and the Whole inclosed in a protecting-sheath of lead or other suitable material or not, as desired. The single conductor 0r pair of conductors thus enveloped, however, Will generally be grouped to form a cable, as shown in Figs. 3 and 4, and the sealing material CZ applied outside the envelope, preferably by immersing the group of conductors forming the cable in a bath of any of the common sealing materials. The lead sheath e is preferably applied after the sealingbath; but it is evident that so far as the present invention is concerned the lead sheath and the method by which it is applied are immaterial.

In addition to the advantages of my sized envelope in preventing` lthe passage of the sealing material to the serving, a very iinportant advantage is obtained in that the continuous glazed surface of the envelope prevents disruptive discharges in the conductor 0r cable. It is found in practice that in certain classes of conductors, including that of my patent above referred to, the most minute crack in the material surrounding the envelope may permit a disruptive discharge under high tension. The possibility of disruptive discharges, however, is largely avoided by a Wrapping of sized paper or other suitable material, and especially when sized with a material which is adhesive when moist, so as to form a continuous glazed surface between the successive folds and which is lexibleivhen dry, so as to prevent the formation of even the most minute cracks.

l. The combination of a conductor, a fibrous or meshed air-containing serving about the conductor, a sized envelope surrounding the served conductor, and sealing material outside the envelope, substantially as described.

2. The combination of a conductor, a librous or meshed air-containing serving aboutthe conductor, an envelope su rrounding the served conductor and sized with a material that is eXible When dry, and sealing material outside the envelope, substantially as described.

3. rlhe combination of a conductor, a fibrous or meshed air-containing serving about the conductor, an envelope consisting of a sized strip Wound about the served conductor, and sealing material outside the envelope, sub stantially as described.

4s. The combination of a conductor, a fibrous or meshed air-containing serving about the conductor, an envelope consisting ot a strip wound about the served conductor and sized with a material that is adhesive when moist, and sealing inaterialoutside the envelope, substantially as described.

5. The combination ot a conductor, a librous or meshed air-containing serving about the conductor, an envelope consisting of a strip Wound about the served conductor and sized with a material that is adhesive when moist and flexible when dry, and sealing material outside the envelope, substantially as described.

G. The combination, with a pair of conductors forming a circuit, and each provided with a fibrous or meshed air-containing serving, of an envelope consisting of a strip Wound about the pair of served conductors and sized with a material that is adhesive when moist and flexible when dry, and sealing material outside the envelope, substantially as described.

7. A cable consisting of a plurality of conductors, each provided with a librous or meshed air-containing serving, envelopes consisting of strips Wound about each conductor or pair of conductors and sized with a material that is adhesive when moist and iiexible when dry, a sheath of lead or other suitable material in which the conductors are inclosed, and sealing material filling the spaces between the envelopes and sheath, substantially as described.

8. The combination of a conductor, an insulatingcoveror servingabout said conductor, a sized envelope surrounding the served conductor, and sealing material outside the envelope, substantially as described.

9. The combination, with a group of conductors, each provided With an insulating coveror serving, of a sized envelope surrounding the group ot' conductors, and sealing material outside the envelope, substantially as described.

10. The combination of a conductor, an insulating cover or serving abou t said conductor, an envelope consisting of a strip wound about the served conductor and sized with a material that is adhesive when moist and iiexible when dry, and sealing material outside the envelope, substantially as described.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

JOHN A. BARRET?.

Titnessesz J. W. MARSH, C. C. WOLFE.

IIO 

